Importance of the biochemical investigations for the functional characterization of a NPC1 variant identified by exome sequencing.

Journal: American journal of medical genetics. Part A

Volume: 

Issue: 

Year of Publication: 

Affiliated Institutions:  Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada. Alberta Newborn Screening and Biochemical Genetics Laboratory, University of Alberta Hospital, Alberta Precision Laboratories, Edmonton, Alberta, Canada.

Abstract summary 

Niemann-Pick disease type C (NPC) is one of the lysosomal storage disorders. It is caused by biallelic pathogenic variants in NPC1 or NPC2, which results in a defective cholesterol trafficking inside the late endosome and lysosome. There is a high clinical variability in the age of presentation and the phenotype of this disorder making the diagnosis challenging. Here, we report a patient with an infantile onset global developmental delay, microcephaly and dysmorphic features, homozygous for c.3560C>T (p.A1187V) variant in NPC1. His plasma oxysterol levels were normal on two occasions. His lyso-sphingomyelin-509 (lyso-SM 509) and urinary bile acid levels were normal. Based on the phenotype and biochemical features, the diagnosis of NPC was excluded in this patient. We emphasize the importance of functional characterization in the classification of novel variants to prevent a misdiagnosis. Matching the phenotype and biochemical evidence with the molecular genomic tests is crucial for the confirmation of genetic diagnoses.

Authors & Co-authors:  Almenabawy Hung Sosova Mercimek-Andrews

Study Outcome 

Source Link: Visit source

Statistics
Citations :  Blom, T. S., Linder, M. D., Snow, K., Pihko, H., Hess, M. W., Jokitalo, E., Veckman, V., Syvänen, A. C., & Ikonen, E. (2003). Defective endocytic trafficking of NPC1 and NPC2 underlying infantile Niemann‐Pick type C disease. Human Molecular Genetics, 12(3), 257–272. https://doi.org/10.1093/hmg/ddg025
Authors :  4
Identifiers
Doi : 10.1002/ajmg.a.63595
SSN : 1552-4833
Study Population
Male,Female
Mesh Terms
Other Terms
Niemann–Pick type C;biomarker;developmental delay;exome sequencing;oxysterol
Study Design
Study Approach
Country of Study
Publication Country
United States